package main

import "fmt"

func main() {
	a := 10
	fmt.Println("函数调用前a的值", a)
	b := &a
	change(b)
	fmt.Println("函数调用之后的a值", a)
	change_1(a)
	fmt.Println("第二次修改a的值后", a)
}
func change(num *int) {
	*num = 20
}

func change_1(num int) {
	num = 30

}
